Summary This article presents a comparative analysis of the concepts of totalitarian democracy and positive liberty in the work of Jacob Leib Talmon and Isaiah Berlin. Its main purpose is to show that a combined analysis of Talmon and Berlin's biographical relationship and their individual texts demonstrates that Talmon's idea of totalitarian democracy may have had a greater influence on Berlin's notion of positive liberty than Berlin seems to have ever acknowledged. The article first summarises the intellectual and biographical relationships (...) that tied these two authors together in a personal friendship and an intellectual fellowship that lasted for more than three decades. In the second part, the insights drawn from the investigation of the authors' intellectual and biographical relationships are linked to an analysis of their texts, The Origins of Totalitarian Democracy and Two Concepts of Liberty. Finally, in the third part of the article, three crucial aspects of Talmon's definition of totalitarian democracy are considered: the interpretation of the Enlightenment and Rousseau's thought, the view of the French revolution, and the possible impact each of these has on subsequent Marxist and socialist reflection, to see how they are addressed in Berlin's idea of positive liberty. (shrink)